Left ventricular dysfunction (LVD) is a symptom of a variety of cardiac disorders. For example, LVD may be caused by dilated cardiomyopathy or ischemia. LVD may also be caused by left bundle branch block (LBBB), which is a conduction disorder that may cause ventricular dysynchrony.
In any particular patient, a single cardiac disorder may cause LVD. However, such disorders often have complicated cause-and-effect interrelationships, and LVD in any particular patient is most often caused by the progression of two or more such disorders. Moreover, some disorders, such as dilated cardiomyopathy, become progressively worse in an attempt to overcome LVD, which ultimately leads to even more severe LVD.
LVD refers to the ineffectiveness of a heart, and more particularly the left ventricle of the heart, as a pump for blood. Patients with LVD may experience fatigue, dizziness, disorientation, edema, shortness-of-breath, end-organ failure, and a host of other symptoms associated with insufficient cardiac output and congestive heart failure. Patients with diagnosed LVD may be treated with drugs, such as beta-blockers, ACE inhibitors, or inotropic drugs. Beta-blockers and ACE inhibitors increase the effectiveness of the left ventricle by decreasing the resistance faced by the left ventricle, and inotropic drugs increase the effectiveness of the left ventricle by increasing the contractility of the heart. In some cases, patients with diagnosed LVD may receive a pacemaker that paces the heart in a way that resynchronizes ventricular contractions and increases the effectiveness of the left ventricle.
Although LVD could be defined in terms of cardiac output, i.e., the volume of blood pumped by a heart per minute, LVD is generally diagnosed when the left ventricular ejection fraction (LVEF) falls below a threshold, e.g., 0.40. In any event, both cardiac output and LVEF must generally be measured in a clinical setting, and tests to assess cardiac output and LVEF are generally not performed unless the patient is symptomatic. LVD can progress from onset to a life-threatening condition quite rapidly. Thus, LVD is frequently not detected and diagnosed until a patient experiences symptoms sufficient to cause hospitalization, at which time the disorders underlying the LVD may have already progressed substantially.